1. Field of the Invention
The present invention relates to an apparatus for and a method of controlling an engine provided with: a variable operation angle mechanism which varies a valve operation angle of an engine valve driven by a camshaft and varies a center phase of the valve operation angle in response to a variation in the valve operation angle; and a variable valve timing mechanism which varies a rotating phase of the camshaft relative to a crankshaft.
2. Description of the Related Art
Japanese Laid-open (Kokai) Patent Application Publication No. 2005-291014 discloses a variable operation angle mechanism suitable for use in an engine to decrease a valve lift amount and to vary a center phase of a valve operation angle in an advance direction in response to a decrease in the valve operation angle of an intake valve.
Incidentally, in the case where there is employed the combination of the variable operation angle mechanism which varies the center phase of the valve operation angle in response to the variation in the valve operation angle and a variable valve timing mechanism which varies a rotating phase of a camshaft relative to a crankshaft of an engine, even if the rotating phase at that time controlled by the variable valve timing mechanism is kept at an identical condition, the center phase of the valve operation angle might varies depending on the valve operation angle at that time.
Thus, even if the variable valve timing mechanism is controlled based on a desired center phase of the valve operation angle that is demanded depending on an engine operating state, an actual center phase might be shifted from the target center phase depending on how extent the valve operation angle is taking at that time.